14.2. Native Event system

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If you have to react to particular events in the persistence layer, you can also use the Hibernate _event_ architecture.
The event system can be used in place of or in addition to interceptors.

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Many methods of the `Session` interface correlate to an event type.
The full range of defined event types is declared as enum values on `org.hibernate.event.spi.EventType`.
When a request is made of one of these methods, the Session generates an appropriate event and passes it to the configured event listener(s) for that type.

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Applications are free to implement a customization of one of the listener interfaces (i.e., the `LoadEvent` is processed by the registered implementation of the `LoadEventListener` interface), in which case their implementation would
be responsible for processing any `load()` requests made of the `Session`.

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The listeners should be considered stateless; they are shared between requests, and should not save any state as instance variables.

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A custom listener implements the appropriate interface for the event it wants to process and/or extend one of the convenience base classes
(or even the default event listeners used by Hibernate out-of-the-box as these are declared non-final for this purpose).

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Here is an example of a custom load event listener:

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<div class="title">Example 341. Custom `LoadListener` example</div>
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<pre class="prettyprint highlight">`EntityManagerFactory entityManagerFactory = entityManagerFactory();
SessionFactoryImplementor sessionFactory = entityManagerFactory.unwrap( SessionFactoryImplementor.class );
sessionFactory
    .getServiceRegistry()
    .getService( EventListenerRegistry.class )
    .prependListeners( EventType.LOAD, new SecuredLoadEntityListener() );

Customer customer = entityManager.find( Customer.class, customerId );`</pre>
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